Pulmonary II Flashcards
(144 cards)
1
Q
Graham’s Law
A
Diffusion is proportional to solubility and 1/sqrt(MW)
2
Q
Which gas is diffusion limited?
A
Carbon monoxide
3
Q
Which gases are perfusion limited?
A
nitrous oxide, oxygen, and carbon dioxide
- however, CO2 may be diffusion-limited in a person with an abnormal alveolar-capillary barrier
4
Q
What determines the amount of gas taken up in perfusion-limited gases?
A
blood flow
5
Q
What determines the amount of gas taken up in diffusion-limited gases?
A
diffusion
(alveolar-capillary membrane)
6
Q
When will oxygen act as a diffusion-limited gas?
A
- during high cardiac output
- decrease inhaled partial pressure of O2
- thickened alveolar-capillary membrane
7
Q
What (4) conditions decrease the diffusion capacity?
A
- thickened barrier
- interstital/alveolar edema or fibrosis
- scleroderma
- interstital/alveolar edema or fibrosis
- decreased surface area
- emphysema
- low cardiac output
- decreased uptake by erythrocytes
- anemia
- ventilation-perfusion mismatch
8
Q
(4) Factors that increase diffusion
A
- increased pulmonary capillary blood volume
- polycythemia
- supine position
- exercise
9
Q
Diffusion Capacity of Lung Equation
A
- V is the amount of gas transferred (diffused)
- P1 & P2 are partial pressures for alveolar & capillary blood (∆P)
- Since there is no CO in capillary blood, Carbon Monoxide is the volume transferred in ml/min/mmHg of alveolar partial pressure
- DLCO is used clinically to evaluate the alveolar-capillary membrane
10
Q
Normal PFT Tests for 40 y.o. male
A
- VC
- 5
- RV
- 1.8
- TLC
- 6.8
- FRC
- 3.4
- FEV-1
- 4
- MVV
- 168 L/min
- DLCO
- 33 mL/min/mmHg
11
Q
PFT are compared based on what factors?
A
height, weight, age, sex, and race
12
Q
What tests measure lung volumes?
A
spirometry, He or Xe dilution, and body plethysmography
13
Q
Flow volume loop for forced and normal breathing
A
14
Q
Flow-Volume Loop for Obstructive Disorder
A
- prolongation of expiration
- MEF < MIF
- Examples: emphysema and asthma
15
Q
Flow-Volume Loop for Restrictive Disorder
A
- narrowed loop due to diminished lung volumes
- greater airflow due to increased elastic recoil
- Ex: interstital lung disease and Kyphoscholiosis
16
Q
Flow-Volume Loop for Fixed Obstruction of Upper Airway
A
- top and bottom of loops are flattened
- fixed obstruction limits flow equally during inspration and expiration
- MEF = MIF
- Ex: tracheal stenosis and goiter
17
Q
Flow-Volume Loop for Variable Extrathoracic Obstruction
A
unilateral vocal cord paralysis or vocal cord dysfunction
18
Q
Flow-Volume Loop for Variable Intrathoracic Obstruction
A
- during forced inspiration, negative pleural pressure holds trachea open
- Ex: tracheomalacia
19
Q
FEV-1
A
- % of the vital capacity
- standard index for assessing airflow limitation
20
Q
Normal FEV-1
A
> 80%
21
Q
FEV-1 graph
(normal vs restrictive vs obstructive)
A
22
Q
Changes in respiratory variables in Obstructive Disease
A
- decrease
- VC
- FEV-1/FVC
- maximal expiratory flow
- maximal breathing capacity
- DLCO (especially with COPD)
- Increase
- Total lung capacity
23
Q
Chances in respiratory variables in Restrictive diseases
A
- decrease
- vital capacity
- total lung capacity
- FEV-1/FVC ratio
- DLCO (very large decrease)
24
Q
A patient reports SOB and fatigue during exercise. The pulmonary function test reveals a normal FEV1/FRC ratio and decreased DLCOSB. What is the most likely diagnosis?
A
pulmonary fibrosis
25
Overall pulmonary vascular resistance is increased by \_\_\_\_\_
hypoxemia
| (due to HPV)
26
Henry's Law
Vgas = Cs \* Pgas
27
Dissolved O2 in Blood
* 1% of total O2 is dissolved
* 0.003 mL/dL/mmHg
* Normally 0.25 mL/dL
* Only dissolved oxygen in plasma exerts a partial pressure
28
Chemical theor predicts that ____ mL of O2 binds wtih 1g of Hb
1.39
29
Mixed venous blood has an O2 saturation of \_\_\_\_
75%
* PO2 40 mmHg
30
At what pressure does 90% saturation occur?
60 mmHg
31
What factors cause a shift in the OxyHb Curve?
* temperature
* pH
* 2,3-DPG
* PCO2
32
What shifts the OxyHb curve to the right?
* decrease pH
* Increase:
* PCO2
* temperature
* 2,3-DPG
A shift to the right has a better unloading of oxygen off of hemoglobin
33
Oxygen Content equation
CO2 = (0.0031 \* PO2) + (1.31 \* Hb \* SO2)
* PaO2 predicted by age:
* 102 - Age/3
34
Effects of Carboxyhemoglobin
left-ward shift of OxyHb curve and decreased oxygen utilization
35
At what %COHb will a patient become unconscious?
40-60%
36
At what %COHb will a patient have impaired vision and temporal discrimination?
5%
37
Half-Life of CO on 100% Oxygen
1-2 hours
38
Half-Life of CO in Hyperbaric Chamber
22 minutes
39
Methemoglobin - Mechanism of Action
Fe2+ is oxidized to Fe3+
* cannot bind O2
* causes the other 3 Fe2+ molecules to increase their binding affinity for oxygen
* will not release into tissues
40
Common Sources of Methemoglobin
* Benzocaine
* Primaquine
* Dapsone
* Nitrates and Nitrities
* Smoke inhalation
41
What % Methemoglobin is first diagonsed with cyanosis?
10-15%
42
Treatment of Methemoglobin
Methylene Blue
* 1-2 mg/kg over 3-5 minutes
* use carefully in patients with G6PD deficiency
* total dose of 15 mg/kg may induce hemolysis
43
Sulfhemoglobin - Mechanism of Action
sulfur atom incorporated into the porphyrin ring
* incapable of binding oxygen
* green pigmentation
* favors sickling in HbS
44
Common Sources of Sulfhemoglobin
* Sulfonamides
* Phenacetin
* Dapsone
* Metoclopromide (in repeated doses)
* sulfur dioxide and hydrogen sulfide
45
Sulfhemoglobin - Signs and Symptoms
* Cyanosis without respiratory distress
* 7-10% SulfHb produces obcious cyanosis
* reduces affinity of unaffected Hb molecules for oxygen
* unlike MetHb
46
Treatment of Sulfhemoglobin
no effective therapy
* possible to RBC transfusion
47
deoxygenated blood that bypasses the pulmonary circulation is called:
shunt
| (venous admixture)
48
What drug may cause sulfhemoglobinemia and turn the patient's blood green?
Sumatriptan
| (imitrex)
49
Sickle Cell Anemia (HbS)
Valine replaces Glutamic Acid on position 6 of Beta chain
* decrease solubility of deoxyHb
* more prone to hemolysis
* Sickling at PaO2 \< 40 mmHg
50
How long do Sickle Cell RBCs usually last?
10-20 days
51
Considerations for Sickle Cell
* avoid dehyration
* keep Hb below 11g/dL
* avoid acidosis and hypothermia
* treat pain promptly
52
Fetal Hb
* leftward shift of O2 dissociation curve
* greater affinity enhances loading of oxygen into fetal blood
* P50 of 19-20 mmHg
* adult P50 = 27
53
Oxyhemoglobin Dissociation Curve Comparison
54
How is CO2 transported in the blood
* Dissolved 10%
* Bicarbonate 60%
* Carbamino compounds 30%
55
What catalyzes the reaction of CO2 and H2O into H2CO3?
Carbonic Anhydrase
* none available in plasma
* reaction is very slow
56
What inhibits Carbonic Anhydrase?
* thiazide diuretics
* acetazolamide
57
What %CA must be blocked to alter CO2 transport?
98%
58
What alters CO2 content?
* PCO2
* temperature
* amount and function of CA
* O2 saturation
59
Normal Venous and Arterial values of CO2
52 mL/dL and 48 mL/dL
| (venous and arterial)
60
How man L of CO2 and Bicarb are stored in the body?
120L
* changes in ventilation alter CO2 less slowly
* normally takes 20-30 minutes
61
How quickly does PaCO2 rise in apnea?
3-6 mmHg/min
62
During a period of apnea, which value will change most rapidly? PaO2 or PaCO2?
PaO2
63
Oxygen Delivery to Tissues
| (equation)
DO2 = Q \* CaO2
64
Oxygen Uptake by Tissues
| (equation)
VO2 = Q \* (CaO2 - CvO2)
65
(5) causes of hypoxemia
* hypoventilation
* low PiO2
* diffusion abnormality
* ventilation-perfusion mismatch
* pure shunt
66
Pulmonary effects of Hypoxemia
tachypnea, pulmonary vasoconstriction
67
Cardiac effects of Hypoxemia
* Early
* increased HR, HTN, and arrhythmias
* Late
* bradycardia, hypotension, and arrest
68
Neurologic effects of Hypoxemia
restless, confusion, increased ICP, obtundation
69
Metabolic effets of Hypoxemia
metabolic lactic acidosis
70
Pulmonary effects of Hypercapnia
tachypnea, pulmonary vasoconstriction, and bronchodilation
71
Cardiac effects of Hypercapnia
Hypertension, tacycardia, and arrhythmias
72
Neurologic effects of Hypercapnia
increased ICP and obtundation
73
Metabolic effects of Hypercapnia
respiratory acidosis and hyperkalemia
74
Normal rate of alveolar ventilation
4 - 6 L/min
75
Rate of pulmonary blood flow
equal to cardiac output
76
V/Q range in the lung
0. 8 - 1.2
* determines the alveolar partial pressures of oxygen and carbon dioxide
77
If V/Q in an alveolar-capillary decreases....
* removal of oxygen relative to delivery will increase
* decrease in PO2 and increase in PCO2
78
An otherwise normal person is brought to the emergency department after having accidentally aspirated a foreign body into the right main-stem bronchus, partially occluding it. What is likely to occur?
* The right lung’s PAO2 will be lower and its PACO2 will be higher than those of the left lung .
* The calculated shunt fraction (QS/Qt) will increase
* Blood flow to the right lung
* Arterial PO2 will fall
79
A normal person lies down on her right side and breathes normally. Her right lung, in comparison to her left lung, will be expected to have a \_\_\_\_\_
* Lower PAO2 and a higher PACO2
* Higher blood flow per unit volume
* Greater ventilation per unit volume
80
Which of the following conditions are reasonable explanations for a patient’s decreased
static pulmonary compliance?
## Footnote
a. Decreased functional pulmonary surfactant
b. Fibrosis of the lungs
c. Surgical removal of one lobe
d. Pulmonary vascular congestion
e. All of the above
all of the above
81
Which of the following tend to increase airways resistance?
## Footnote
a. Stimulation of the parasympathetic postganglionic fibers innervating the bronchial
and bronchiolar smooth muscle
b. Low lung volumes
c. Forced expirations
d. Breathing through the nose instead of the mouth
e. All of the above
all of the above
82
Which of the following statements concerning alveolar pressure is/are correct?
## Footnote
a. Alveolar pressure is lower than atmospheric pressure during a normal negativepressure inspiration.
b. Alveolar pressure is greater than atmospheric pressure during a forced expiration.
c. Alveolar pressure equals the sum of the intrapleural pressure plus the alveolar elastic recoil pressure.
d. Alveolar pressure equals atmospheric pressure at the end of a normal tidal expiration.
e. All of the above.
all of the above
83
Which of the following statements concerning small airways is/are true?
## Footnote
a. The total resistance to airflow decreases with successive generations of airways because there are increasing numbers of units arranged in parallel.
b. The linear velocity of airflow decreases as the airways decrease in size because their total cross-sectional area increases.
c. Alveolar elastic recoil plays an important role in determining the resistance to airflow in small airways because alveolar septal traction helps to oppose dynamic compression.
d. Airflow in small airways is usually laminar.
e. All of the above.
all of the above
84
Which of the following statements concerning pulmonary mechanics during the early
portion of a forced expiration, when lung volume is still high, is/are correct?
## Footnote
a. There is less alveolar elastic recoil at high lung volumes than there is at low lung
volumes.
b. Airways resistance is greater at high lung volumes than it is at low lung volumes.
c. There is more dynamic compression of airways at high lung volumes than there is at
low lung volumes.
d. The effective pressure gradient for airflow is greater at high lung volumes than it is at
low lung volumes.
85
Which of the following conditions are reasonable explanations for a patient’s functional
residual capacity that is significantly less than predicted?
## Footnote
a. Third trimester of pregnancy
b. Pulmonary fibrosis
c. Obesity
d. Emphysema
e. All of the above
f. a, b, and c
third trimester, pulmonary fibrosis, and obesity **decrease** FRC
86
A subject starts at her FRC and breathes 100% O2 through a 1-way valve. The expired air is
collected in a very large spirometer. The test is continued until the expired N2 concentration is virtually zero. At this time, there are 36L of gas in the spirometer, of which 5.6% is N2. What is the subject’s FRC?
* volume N2 in spirometer
* 0.056 \* 36 L = **2.0L**
* Since N2 is 80% of her FRC
* 100/80 \* 2L = **2.5L**
87
A patient’s mean arterial blood pressure is 100 mmHg and his right atrial pressure is 2 mmHg. His mean pulmonary artery pressure and pulmonary capillary wedge pressure are 15 and 5 mmHg,
respectively. If his cardiac output is 5 L/min, calculate his pulmonary vascular resistance
and systemic vascular resistance.
* Pulmonary Vascular Resistance
* PVR = (MPAP - MLAP)/Q
* 2 mmHg/L/min
* Systemic Vascular Resistance
* SVR = (MABP - RAP)/Q
* 19.6 mmHg/L/min
88
Which of the following situations would be expected to decrease pulmonary vascular
resistance?
## Footnote
a. Ascent to 15,000 ft above sea level
b. Inspiration to the total lung capacity
c. Expiration to the residual volume
d. Moderate exercise
e. Blood loss secondary to trauma
only **moderate exercise** would cause a decrease in PVR
89
Which of the following situations would be expected to lead to an increase amount of the
lung under zone 1 conditions?
## Footnote
a. Ascent to 15,000 ft above sea level
b. Blood loss secondary to trauma
c. Moderate exercise
d. Positive-pressure ventilation with positive end-expiratory pressure (PEEP)
e. Changing from the standing to the supine position
blood loss and PEEP
90
Which of the following circumstances might be expected to contribute to the formation
of pulmonary edema?
## Footnote
a. Overtransfusion with saline
b. Occlusion of the lymphatic drainage of an area of the lung
c. Left ventricular failure
d. Low concentration of plasma proteins
e. Destruction of portions of the pulmonary capillary endothelium by toxins
f. All of the above
all of the above
91
How does changing from **supine to upright** change the diffusing capacity of the lungs?
decreases
* decrease in venous return because of pooling of blood in extremities
* decreased venous return decreases CBV and may decrease right ventricular output
* Therefore, recruitment of pulmonary capillaries and decreased surface area for diffusion
92
How does exercise affect the diffusion capacity of the lungs?
Increases
* increase in CO recruits underperfused capillaries
93
How does the Valsalva maneuver affect the diffusion capacity of the lungs
decreases
* greatly decreases the pulmonary blood volume
94
How does anemia affect the diffusion capacity of the lung?
decreases
* decreases the hemoglobin available
* partial pressure of O2 in the plasma equilibrates more rapidly with the alveolar PO2, leading to increased perfusion limitation
95
How does a low cardiac output affect the diffusion capacity of the lungs?
decreases
* decreases the venous return and central blood volume
* pulmonary capillary blood decreases, resulting in derecruitment and decreased surface area
96
How does interstital fibrosis of the lungs affect their diffusion capacity?
decrease
* According to Fick's law:
* thickening of alveolar-capillary barrier
97
How does Emphysema affect the diffusion capacity of the lungs?
decrease
* destroys the alveolar interstitum of blood vessels and thereby decreasing the surface area
98
If the pulmonary capillary partial pressure of a gas equilibrates with that in the alveolus before the blood leaves the capillary
its transfer is said to be perfusion limited.
99
An otherwise normal person has lost enough blood to decrease his body’s hemoglobin concentration from 15 g/100 mL blood to 12 g/100 mL blood. What would be expected to decrease?
Blood oxygen-carrying capacity and arterial oxygen content
100
Voluntary apnea for 90 seconds will
* increase PCO2
* decrease PO2
* stimulate arterial and central chemoreceptors
101
Which of the following conditions would be expected to stimulate the arterial chemoreceptors?
## Footnote
a. Mild anemia
b. Strenuous exercise
c. Hypoxia due to ascent to high altitude
d. Acute airway obstruction
e. Large intrapulmonary shunts
a,b,c, and d
* arterial chemoreceptors are stimulated by low arterial PO2 rather than by a low oxygen content
102
Stimulation of which receptors of the following should result in decreased ventilation?
## Footnote
a. Aortic chemoreceptors
b. Carotid chemoreceptors
c. Central chemoreceptors
d. Hering-Breuer inflation (stretch) receptors
central chemoreceptors
103
Which of the following would be expected to decrease the ventilatory response to carbon dioxide, shifting the CO2 response curve to the right?
## Footnote
a. Barbiturates
b. Hypoxia
c. Slow-wave sleep
d. Metabolic acidosis
e. Deep anesthesia
barbituates, slow-wave sleep, and deep anesthesia
104
normal resting oxygen consumption of an adult
250-300 mL O2/min
105
average Oxygen-carrying Capacity
1.34 mL O2/Hb
106
What determines the amount of oxygen that binds to hemoglobin
PO2 of the plasma
107
normal PO2 of mixed venous blood
40 mmHg
108
At what PO2 is hemoglobin about 75% saturated?
40 mmHg
109
At what PO2 is hemoglobin fully saturated
250 mmHg
110
For any PO2, there is less oxygen bound to hemoglobin at \_\_\_\_\_\_
(shifting curve to the right)
higher temperatures
lower pHs (acidic)
higher PCO2
elevated 2,3-BPG
111
Haldane effect
deoxygenation of the blood increases its ability to carry carbon dioxide
112
Dorsal Respiratory Group
* located in NTS
* consist mainly of inspiratory neurons
* drive for diaphragm
* timing of respiratory cycle
113
Where are the centers that initiate breathing located?
reticular formation of the medulla
(beneath the floor of the 4th ventricle)
114
locations of Ventral Respiratory Group
retrofacial nucleus
nucleus ambiguus
nucleus para-ambigualis
nucleus retroambigualis
115
Nucleus Ambiguous
vagal motorneurons in the VRG
* innervate larynx, pharynx, and tongue
116
Nucleus Retroambigualis
expiratory neurons of the VRG
* coordination of respiration
117
Nucleus Para-Ambigualis
inspiratory neurons of the VRG
* controls force of contraction of contralateral inspiratory muscles
118
Botzinger Complex
group of expriatory neurons in the VRG
* inhibits inspiratory neurons in the DRG
119
Respiratory Neurons
| (picture)
* gray - inspiratory
* blue - expiratory
* broken lines - expiratory pathways that inhibit inspiration
* BC - Botzinger Complex
120
Excitatory neurotransmitters in ventilation
Glutamate
* NMDA receptor
121
Inhibitory neurotransmitters in ventilation
GABA and Glycine
* hyperpolarize neuron and inhibit activity
122
Pontine Respiratory Group (PRG)
fine control of respiratory rhythm
* Three groups:
* inspiratory, expiratory, and phase spanning
* modulates response to hypercapnia and hypoxia
123
Onedine's Curse
congenital central hypoventilation syndrome (CCHS) or primary alveolar hypoventilation
* breathing is voluntary
* Polio and CVA
124
Sensors and Reflexes of the Larynx
dense sensory innervation
* mechanoreceptors, cold receptors, and irritant receptors
* subglottic: recurrent laryngeal
* supraglottic: superior laryngeal
* bronchoconstriciton, cough, laryngospasm
125
SAR of the Lungs
Slowly Adapting Receptors in the airways that respond to stretch
126
RAR of the Lungs
Rapidly Adapting Receptor in superficial mucosa
127
J Receptors
| (juxtapulmonary)
located in the walls of pulmonary arteries
* stimulated under pathological conditions
* tissue damage, PE
* stimulates tachypnea and dyspnea in pulmonary vascular congestion
128
Hering-Breuer Inflation Reflex
inhibition of inspiratino in response to an increase pulmonary transmural pressure gradient
* in VT \> 1 L
129
Hering-Breuer Deflation Reflex
shortens exhalation and helps maintain infants FRC
* augmentation of inspiration in response to deflation of lungs
* may be inolved in spontaneous "sighs" to prevent atelectasis
130
Paradoxical Reflex of Head
sudden inhalation causes increased inspiratory effort
* "gasp" reflex
* often occurs upon induction
131
Central Chemoreceptors
monitors steady-state PCO2
* anterolateral surface of medulla
* responsible for 80% of total respiratory response
* respond to arterial and CSF PCO2
* compensatory bicarbonate shift
* CO2 crosses the BBB
132
Peripheral Chemoreceptors
detect changes in PO2, PCO2, and H+
* fast response
* carotid bodies \> aortic bodies
* stimulated by:
* decreased PO2, pH
* blood temperature, hypoxia, chemicals
133
(2) Hypoxic Ventilatory Responses
Acute isocapnic hypoxia and Poikilocapnic hypoxia
134
(3) Phases of Acute Isocapnic Hypoxia
* acute hypoxic response
* first immediate and rapid increase in ventilation
* hypoxic ventilatory decline
* minute ventilation declines after reaching plateau
* ventilatory response to sustained hypoxia
* slow rise in ventilation over several hours
135
Poikilocapnic Hypoxia
CO2 not controlled and magnitude of response damped
* increase in MV
136
Holding Breath
if air only, 50 mmHg CO2 is the breaking point
* hypoxia \> influence than hypercapnia
137
Opioid effects on Breathing
respiratory depression
* u and S receptors in respiratory center
138
Benzodiazepines effect on Breathing
dose dependent respiratory depression
* ceiling effect
139
Doxapram effect on Breathing
respiratory stimulant
* stimulates peripheral chemoreceptors in increase respiratory drive
* standard dose doubles resting MV and increases ventilatory response
140
basal level of oxygen consumption
200-250 mL/min
141
VO2 Max
oxygen consumption when exercising as hard as possible
* usually 3 L/min for 70kg adult
* can be improved with regular exercise
142
(3) Phases of Ventilatory Response to Exercise
* Phase I
* anticipatory, central command
* Phase II
* increase seen in moderate exervise
* Phase III
* plateau reached during heavy exercise
143
Which body system is the "weak link" in endurance training
Pulmonary system
* no intrinsic capacity for adaptation to endurance
144
90% oxygen saturation occurs at what PO2
60 mmHg
